Industrial and power generation gas turbines include a compressor configured to provide compressed air to the gas turbine, or more particularly to one or more combustors in the gas turbine. Positioned at an inlet of the compressor is a plurality of circumferentially arranged inlet guide vanes (IGVs). The IGVs define an IGV angle that allows them to restrict airflow to the compressor during certain turbine operating modes and/or guide air as it enters the inlet of the compressor.
The IGVs are coupled to an actuator which may adjust the IGV angle. The actuator may include a rack and pinion gear system, wherein a primary gear runs circumferentially around the outside of a compressor casing and engages corresponding pinion gear wheels positioned at an end of each IGV. Rotating the pinion gear wheels at the end of each IGV rotates the IGV about its axis and changes the IGV angle. Thus, when the primary gear rotates circumferentially around the outside of the compressor casing, the pinion gear wheels positioned at the end of each IGV are engaged and correspondingly rotate about their respective axes, and the IGV angle adjusts accordingly.
In some instances, however, a portion of one or more of the pinion gear wheels, a portion of the primary gear, or both become worn. In such a case, one or more pinion gear wheels and corresponding IGVs may individually rotate about their respective axes while the primary gear remains stationary. This wear may be caused, e.g., by vibrations in the compressor while dust, metal fillings, etc. are caught between one or more of the pinion gear wheels and the primary gear. The amount that each of the pinion gear wheels and corresponding IGVs can move about their axes relative to the primary gear is referred to as the amount of “backlash.” When there is backlash in the IGVs, the IGVs can flutter during operation, and when the amount of backlash is higher than a predetermined limit, the fluttering can cause damage to the compressor and the gas turbine.
As such, during e.g., maintenance outages of the gas turbine, it is occasionally necessary to measure the amount of backlash in the IGVs to ensure it is within the predefined limit. This measurement is commonly completed using a measurement device that magnetically mounts to the inside of the compressor casing, next to the IGV to be measured. The measurement device typically includes two or more adjustable linkages to align an indicator perpendicularly to a specific spot on an edge of the IGV. Once mounted and aligned, the indicator is zeroed and a measurement is taken while the IGV is manually moved by a worker. The measurement is typically recorded manually, and the process is repeated for each IGV. Measuring the backlash in the IGVs by such a process and with such a device is time consuming and tedious. For example, it may take two workers up to 18 hours to measure the backlash in each of the IGVs.
Accordingly, an apparatus and method that may reduce the amount of time and effort required to measure the backlash in each of the IGVs may be beneficial.